To reconcile the observations of the relative energies and fluxes of O+ and H+ ions with the high-altitude occurrence of significant parallel ion acceleration, an omnipresent ionospheric energization mechanism that provides at least enough energy (~10eV) to oxygen ions to get them to ~5,000 km has been postulated.

Experimentally, it has been difficult ot acquire information about the altitude distribution of heavy ion energies on magnetic field lines associated with intense ion energyization events to determine the degree of ionospheric preenergization of escaping oxygen ions.

DE -1 and the Akebono satellites obtained a series of coordinated observations at two altitudes on closely spaced auroral field lines.

Detailed examination of the plasma properties from several magnetic conjunction eventswhich are summarized in the tables below and discussed by Peterson et al. (1993) directly demonstrate that preenergization of O+ to energies ~ 10 eV commonly occurs on auroral field lines below the region where significant (i.e. keV) energy parallel to the magnetic field is acquired.

The above data also demonstrate that transport of O+ ions upward and across the polar cap from so-called cleft ion fountain is more complex than previously anticipated.